Hiram d



H. D. CURRIER.

TRUNK c mcun. APPLICATION FILED SEPT. 19.1914.

.1 07,538. Patented June 24, 1919.

ended at one extremity,

UNITED STATES PATENT OFFICE.

HIRAM D. CURRIER, OF CHICAGO, ILLINOIS, ASSIGNOR 'IO KELLOGG SWITCI-IBOARD & SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

V TRUNK-CIRGUIT.

Specification of Letters Patent.

Patented J une 24:, 1919.

Application filed September 19, 1914. Serial No. 862,462.

To all whom it may concern:

Be it known that I, HIRAM D. CURRIER, a citizen of the United States of America, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Trunk- Circuits, of which thefollowing is a specification.

My invention relates to telephone systems and has for its object the provision of means whereby a connected substation after the completion of a conversation is free to mitiate another call irrespective of whether a link or cord circuit remains connected with the line or not.

More particularly my invention is an improvement over the invention disclosed 111 my co pending" application Serial No. 815,122, filed Jan. 29, 1914, in which means are disclosed whereby a connected substation automatically frees itself from the link circuit when the receiver is replaced upon the switch hook.

In my present invention the arrangement is such that only partial restoration of the interconnecting appliances at the central station is necessary in order to free the substation to initiate another call. To show one form of the application of my invention, I may say that it a trunk circuit is used, p'lug then the disconnection of the other extremity of the trunk circuit automatically frees the substation connected with the plug ended portion of the trunk circuit so that this particular substation is permitted to initiate another call even though the plug ended portion of the trunk circuit remains in association with the line circuit of that particular substation.

Of course my invention is not to be so limited to the use in connection with trunk circuits, but in the specific description which follows I will explain more in detail this particular form which my invention may take, this particular description being given in connection with the accompanying drawing illustrating such a system diagrammatically.

In this drawing I show a substation A and a substation B, the substation A extending bv means of the conductors 1 and 2 to a central station 0. This central station C is c onnected by means of the trunk circult having the conductors 3 and 1 with another central station D at which the trunk circuit ends, and at which connection may be made with the incoming line from the substation B. An order wire circuit consisting of the conductors 5 and 6 and associated apparatus is of course also shown for purposes well understood.

In accordance with general practice it is of course understood that the station A in calling for the substation B secures the first connection at the central station C, whereupon the central station C orders up the connection over the trunk wires, whereupon the operator at the station D inserts the plug 7 into the jack 8 of the called for line B. As suming then that the parties are through talking and that the supervision is under the control of the operator at the station C, the operator at the station C removes the cord circuit at said station. The removal of the plug 9 from the jack 10 of the trunk circuit releases the operative control of the'plug ended portion ofthe trunk circuit over the line. circuit instrumentalities of the substation B so that this substation B entirely controls its line lamp 11 and may initiate another call after the plug 9 is removed even though the plug 7 remains in the jack 8.

A great many of the instruments shown are of course standard and it is not thought necessary to go into a detailed description of all of them, but a clear understanding of the invention will be best secured doubtless by describing a connection from the substation A through to the substation B. Y

A removal of the receiver 12 at the substation A actuates the line lamp 13 associated with that substation in theusual way.

The operator at the station C inserts the The operation of the relay 16 actuates the relay 34 as readily apparent. The actuation of the relay 16 of course energizes the lamp 22, whereupon the operator at the station D inserts the plug 7 into the jack 8 to call the substation B. The insertion of the plug 7 as apparent operates the cut-off relay 23 and the relay 24. The ringing key RK is thereupon actuated momentarily completing the contact at the spring 25 to thereby actuate the'relay 26. Actuation of the relay 26 causes it to lock itself at the ground of the operated relay 24. Ringing current is thus sent over the line by the operation of the relay 27 as well understood, and the response of the subscriber at the station E operates the relay 28 as the relay 24 is in its attracted condition. The actuation of the relay 28 causes the actuation of the relay 29 over the ground controlled by the relay 24. The operation of the relay 29 thereupon operates the relay 30 from the battery supplied for the cord circuit at the station C, and this relay 30 being of low resistance shunts the relay 1G and allows it to permit retraction of its armature. The increased flow of current due to this shunt circuit about the relay 16 permits the calling supervisory relay 31 at the station C to respond, thus eXtin guishing supervisory lamp 32. The relay 16 restoring opens the initial energizing circuit of relay 34 but a substitute circuit for relay 34 is established upon the energization of relay 30 traced from battery through the said relay 34 to ground at alternate contact of relay 30. The continued energization of relay 34 prevents the relay 35 from being prematurely placed in circuit relation with relay 23 until conversation has been terminated and the cord C withdrawn from the trunk jack 10. After the conversation is completed, the restoration of the receiver at the station E opens the circuit through the relays 28 and 29 and 30, again placing the relay 16 in circuit and allowing the relay 01 to deenergize, thereby lighting the lamp 32.

It is assumed that the lamp 33 is also lighted by the restoration of the circuit at the substation A. The operator at the station C thereupon removes the cord circuit at that station, permitting the relay 16 to restore. The restoration of the relay 16 pernits restoration of the relay 34, thereby including the relay 35 in circuit with the cutoil relay 23 through the now closed contact 41 of relay 34. The opening of contact 42 of relay 34 opens the initial energizing circuit. of relay 24 but a substitute circuit for relay 24 is established traced from battery through winding of relay 24 to ground at alternate contact 43 of relay 35. The continued energization of relay 24 and the restoration of relays 16 and 30 closes a cir -cuit for lamp 22 traced from battery through the said lamp, alternate contact 44 of relay 24, normal contact 45 of relay 16 to ground at normal contact 40 of relay 30. The lighting of lamp 22 notifies the operator of trunk D that conversation has terminated. The relay 35 being high wound (say 4000 ohms) prevents the actuation of the relay 23, Which thus restores, placing all of the line circuit apparatus associated with the substation B in condition for recall and entirely under the control of the switchhook at the substation B. From this it will be apparent that the substation B is in condition to initiate a call immediately the plug 9 has been withdrawn from the trunk circuit, thus preventing said substation from being hung up due to the non-removal of the plug 7.

From this description of one specific form of the invention its nature will undoubtedly be clear to those skilled in the art, and it will also be clear that changes and modifications herein can be readily made without departing from the spirit of my invention. Having however thus described one form which my invention may take, what I claim as new and desire to secure by Letters Patent is:

1. A telephone system including a calling and a called subscribers telephone line, a link circuit for use in connecting said lines, terminals for said link circuit normally operatively associated therewith, and means operative prior to a response being had from the called subscriber for operatively disassociating said link circuit from the called subscribers line, controlled solely by the disconnection of one of the said link circuit terminals from the calling line.

2. A telephone system including a calling subscribers line and a called subscribers line, an operator-controlled link circuit having manual connection terminals normally operatively associated therewith for connecting said lines in conversational circuit, and means operative prior to the response being had from the called subscriber for operatively disassociating said link circuit from said called line, controlled solely by the disconnection of one of the terminals of said link circuit from the calling subscribers line.

3. A telephone system comprising a calling subscribers line and a called subscribers line, an operators link circuit and an operators trunk circuit for use in connecting said lines in conversational circuit, manual terminals for said trunk circuit both normally operatively assooiated'therewith for extending a connection to the said called line, automatic ringing means for said trunk circuit for intermittently and automatically applying ringing current to the called sub scribers line, means controlled by the response of the called subscriber for disassociating the said ringing means from said called line, and means controlled by the dis- AA telehpone system comprising .a calling subscriber s line and a called subscribers line, an A-operatorsl nkc rcuit and a B5 operators trunk circuit for connecting said lines in a conversational circuit,a manual;

connection terminal for said trunk circuit normally operatively associated therewith,

and means controlled by the disconnection of said link circuit-from saidtrunk circuit. for; operatively releasing the called connected line to permit recall by sa1dcalled subscriber prior to the removal otsaid connectlon ter 1 minal from the jack of said called line.

5. A telephone system having a plurality of entering lines, a cord circuit forintercom necting said lines, and means controlled by the disconnection of one terminal of a connected cord, circuit from one connected line for operatively disassociating said cord circuit from -the other connected line, said means including ahigh resistance magnet adapted for association with said second line upon thedisconnection aforesaid.

6. A telephone system. comprising a telephone line, an operator controlled cord circuit having a manual connecting terminal for connection with said line as a called line, and means for .ioperatively said cord circuit from said line controlled by the operativedisconnection of the other terminal of said cord circuit from a. connected line, said means including ahighresistance magnet adapted for association ,with' said second line upon the disconnection aforesaid.

7. A telephone system comprising a-plu-- rality of lines entering difierent central stations, a trunk circuit between said central stations for interconnecting telephone lines between said central stations, and means controlled by the operative disconnection of one terminal of a connected trunk circuit to operatively disassociate saidtrunk circuit from the other connected line, said means including a high resistance magnet adapted for association with said second line upon the disconnection aforesaid.

8. A telephone system comprising a plurality of lines entering different central stations, a trunk circuit between said central stations for interconnecting telephone lines between said central stations, and means controlled by the operative disconnection of one terminal of a connected trunk circuit from a line for operatively releasing the other connected line to permit recall by said second connected line, said means including a high resistance magnet adapted for association with said second line upon the dis connection aforesaid.

9. A telephone system comprising a calling subscribers line and a called subscribers line, an operator controlled link circuit prodisassociatmg vided withmanual connection terminals nor? mally associated with-said link circuit for connecting said lines, automatic ringing means forsaid link circuit for intermittently applying ringingcurrent to the called'subscribers line, means controlled by the called subscriber for disassociating said ringing means from said called line, a supervisory signal under the control, of said-calling subscriber, means for operating said signal when said calling subscriber signals for disconnection, and means controlled by the disconnection of said link circuit from said calling subscribers line for ciating said link circuit from said called 10. A telephone ing subscribers line and a called subscribers line, an operator controlled link circuit for connecting said lines in conversational circuit, a supervisory signal, means controlled bysaid calling subscriber for operatingsaid signal'to signal for disconnection, and operator controlled means operable afterv said calling subscriber has signaled for disconnection for operatively disassociating said called subscribers line'from said link circuit,; said means being controlled by the operator disconnecting the said calling subscribers line from said link circuit. I

11. A telephone system including .a calling;subscribers line and a called subscribers operatively disassosystem comprising a call-.

line, an operators link circuit and an operators trunk circuit for connecting said lines, a pair otter'minals for said trunk circuit normally operatively associated with said trunk circuit, means for disconnecting said link circuit from said trunk circuit, and -means,respons1ve to said disconnection for operatively disassociating said called subscribers line from said trunk circuit.

12. A telephone system comprising telephone lines, an operators link circuit and an operators'trunk circuit for interconnecting said lines, terminals for said link circuit normally operatively associated with said link circuit, and means solely controlled by the disconnection of one of said link circuit terminals from said trunk circuit for operatively disassociating said trunk circuit from the called one of said connected lines.

13. A telephone system comprising a plurality of subscribers telephone lines, an op erators link circuit for connecting any two of said lines in conversational circuit, and means under the sole control of the central office operator for operatively disassociating the said link circuit from a connected one of said lines, said means being responsive to the disconnection of said link circuit from the other connected line.

1a. A telephone system including a calling subscribers line and a called subscribers line, an operators link circuit and an operators trunk circuit for connecting said lines in conversational circuit, means under the sole control of a central oflice operator for operatively disconnecting said trunk circuitfrom said called line,"said means being responsive to the disconnection of said link circuit from said trunk circuit.

15. A telephone system including a calling'subscribers line and a called subs'cribers line, an operator-controlled link clrcuit and an operator controlledtrunk circuit connect ing said lines, terminals for said trunk circuit normally operatlvely connected there'- With, a supervisory signal for said link 'circuit under tliecontrol of said calling subscrlber, means for operating said signal when the calling subscriber signals for disconnection, and means controlled by the disconnection of said link circuit from said operatively disassociatmg trunk circuit for said trunk circuit from said called line.

16. A telephone system including a calling subscribers line and a called subscribers line, a manual link circuit and a manual trunk circuit for use in connecting said lines, and means controlled by the disconnection of said link circuit from said trunk circuit, if

both of said subscribershave signaled for disconnection, to -'ope'ratively disassociate said trunk circuit from said called line.

17. A telephone system including a calling subscribers line and a called subscribers line, a manual link circuit and a trunk circuit connecting said lines in conversational circuit, and automatic means controlled by the disconnectionof said link circuit from said trunk circuit after both of said sub- Copies of this'patent may be obtained for live cents each,

scri-ber's have replaced their receivers for operatively 'disassociating' said trunk circuit from the called line.

11-8. A telephone system including a calling'subs'cri befs line and a'called subscribers line, a manual li'nk circuit for connecting said-lines in'conversational circuit, terminals 1 ing manual connection terminals normally.

operatively associated with said link circuit for connecting said lines in conversational circuit, and means for operatively disassociating said link circuit from said called line, after the subscribers have signaled for disconnection, controlled solely by the discone nection of the other terminal of the link circuit from the callin subscribers line.

Signed by me at %hi'cago, coimty'of Cook and State of Illinois, in the presence of two Witnesses.

I HIRAM D. CURRIER.

VVitness'es l GEORGE E. MUELLER, M. R. RooHroRD.

Washington, D. G.

by addressing the Commissioner oi. latents, 

